DE1110418B - Process for the polymerization and interpolymerization of olefins - Google Patents

Description

It is known to use α-olefins and diolefins, in particular Ethylene, propylene and butene- (l) as well as butadiene and isoprene, with catalysts made from compounds of Metals of subgroups V to VIII of the Periodic Table and reducing or alkylating effects Compounds of I. to III. Group of the periodic table at relatively low pressures and To polymerize temperatures to high molecular weight polyolefins. Especially have for such Low pressure polymerizations with catalyst mixtures of titanium tetrachloride or titanium subhalides Aluminum alkyls, which can also contain halogen, have proven successful. The ones in these low pressure polymerization processes Catalysts used are referred to as Ziegler catalysts and are z. B. in the Belgian patent 533 362.

In the polymerization of propylene and the higher α-olefins with the aforementioned catalysts are in addition to well crystalline hydrocarbons used as dispersants under the polymerization conditions insoluble or sparingly soluble polymers also amorphous, Easily soluble polymers and oils are obtained. According to Natta, these are polymers that crystallize well sterically ordered and are referred to as "isotactic", while the soluble polymers are sterically are disordered and are called "atactic".

Little is known about the mechanism of action of the Ziegler catalysts. It has been shown that the reaction of TiCl ₄ and organoaluminum compound results in a reduction of the tetravalent titanium. For example, the reaction of TiCl ₄ with AlR ₃ creates a trivalent titanium compound that can be further reduced to divalent titanium.

Ti Cl ₄ + AlR ₃ - *. R '+ Ti Cl ₃ + Al R ₂ Cl

(Equation I)

TiCl ₃ + AlR ₃ - * R '+ TiCl ₂ + AlR ₂ Cl

(Equation II)

When using halogen-containing aluminum alkyl compounds, such as mono- or dialkyl halides of the type AlR ₂ Hal or AlRHaI ₂ (R = alkyl) or a mixture of these compounds, the sesqui halides, a reduction occurs only up to the trivalent Ti compound, e.g. B.

TiCl ₄ + AlR ₂ Hal

TiCl ₄ + AlRHaI ₂

TiCl ₃ + AlRHaI ₂ + R '

(Equation III)

- ». TiCl ₃ + AlHaI ₃ + R '

(Equation IV)

Polymerization process
and interpolymerization of olefins

Applicant:

Farbwerke Hoechst Aktiengesellschaft

formerly Master Lucius & Brüning,

Frankfurt / M., Brüningstr. 45

Dr. Kurt Rust, Frankfurt / M.,

Dr. Siegfried Sommer, Frankfurt / M.-Unterliederbach, and Dr. Werner Bartsch, Hofheim (Taunus),

have been named as inventors

In the polymerization of α-olefins of the R — CH = CH _{2 type} , where R = H or a hydrocarbon radical "means up to 8 carbon atoms, it has been found that the presence of aluminum monoalkyl dihalides in particular has an unfavorable influence on the rate of polymerization In an older invention, which does not belong to the state of the art, it has therefore been proposed, in the ethylene polymerization, to use inert solvents such as low-olefin petroleum fractions, saturated aliphatic or cycloaliphatic hydrocarbons, wash. through an intensive washing process the bulk of the Aluminiummonoalkyldihalogenids from the TiCl ₃ suspension is removed. such TiCl ₃ provides in ethylene polymerization with respect to polymerization and molecular weight reproducible results than unwashed TiCl _3. in the Polymerization of α-olefins, in particular propylene, is carried out with a well-washed TiCl ₃ with a suitable activation, e.g. B. with dialkyl aluminum monochloride, a satisfactory space-time yield and a largely sterically uniform, isotactic polymer obtained.- According to an older, not part of the prior art proposal, the stereospecificity can be increased if

109 620/469

the TiCLj precipitation of a thermal treatment subjects and washes before and / or after the heat treatment.

The activity of this separated, washed, thermally treated Ti Clj precipitate can be further according to an older proposal, which is not part of the state of the art, is increased considerably are, if one uses an activator, in addition to metal alkyl halides, the halogen being a Has an atomic weight> 35, also contains metal alkyl fluoride. Such activators can be easily prepared, inter alia, by using metal alkyl halides (Halogen atomic weight> 35) reacts with fluorides, which easily convert their fluorine against chlorine, bromine or iodine change. As such fluorides are, for. B. the alkali or alkaline earth fluorides and / or heavy metal fluorides to mention.

Furthermore, the polymerization of olefins can be simplified and cheaper according to a proposal, which is also not part of the state of the art, if catalyst mixtures are used which are obtained by treating the in the reaction of heavy metal compounds, eg. B. of titanium tetrachloride, and organoaluminum compounds obtained reaction mixture with aluminum trialkyls. The great advantage of this procedure is that the aluminum monoalkyl dichloride contained in the mother liquor according to equation III is converted into the polymerization-active aluminum dialycl monochloride according to equation V and the _{organoaluminum compound used to reduce the TiCl 3 is} largely used for the polymerization, while it is discarded in the washing process .

Al (C ₂ H ₅ ), + Al (C ₂ H ₅ ) Cl ₂ -

-2Al (C ₂ Hg) ₀ Cl
(Equation V)

Another great advantage is that the difficult filtration of the _{TiCl 3} suspension can be avoided during the washing process and no solvent has to be used for a washing process. According to the last-mentioned older proposal, _{such an amount of aluminum trialkyl is added to the unwashed TiCl 3} suspension that is sufficient to convert the aluminum monoalkyl dichloride formed during the TiCl ₃ production into aluminum dialkyl monochloride.

To use for the preparation of TiCl _3, the reaction of TiCl ₄ with aluminum-organic compounds without further treatment (washing, thermal treatment or Aluminiumtrialkylbehandlung), as has been described by Natta et al (Gazz. Chim. V Ital., 87, Fase. , P. 528, 549, 570 [1957]), the result is normally catalysts which are only slightly selective in the α-olefin polymerization. In contrast, according to Natta (cf. literature above), selectively acting contacts are obtained from aluminum triethyl and microcrystalline TiCl _{3 , which is produced from TiCl 4} and H ₂ by the technically more difficult method to be carried out at high temperatures. However, the rate of polymerization is considerably slower than with a _{TiCl 3 produced from TiCl 4} and an organoaluminum compound which has been post-treated, as mentioned above.

It has now been found that homopolymers and copolymers of olefins of the general formula CH ₂ = CHR, where R is hydrogen or a hydrocarbon radical of up to 8 carbon atoms, with catalysts made from reducible compounds of heavy metals from IV. To VI . Subgroup of the Periodic Table, especially TiCl ₄ , and organoaluminum compounds, which may also contain halogen, can be prepared by using catalysts for the polymerization which are obtained by treating the heavy metal compounds, e.g. B.

ίο TiCl ₄ , and organoaluminum compounds resulting reaction mixture with aluminum trialkyls or aluminum triarylene, the hydrocarbon radical of these aluminum compounds containing 1 to 6 atoms, and metal fluorides, in particular alkali metal fluorides, have been obtained or are formed during the polymerization.

It was further found that the composition of the mixture of aluminum trialkyl and metal fluoride is advantageous such that the sum of

ao aluminum trialkyl (in moles) and metal fluoride (in moles) is approximately the same as the amount of aluminum monoalkyl dihalide (in moles) that is produced during the establishment of the contact, e.g. B. that the molar ratio of aluminum trialkyl to metal fluoride to aluminum monoalkyl dihalide is 0.1: 0.9: 1 to 0.9: 0.1: 1.

The great advantage of this procedure according to the invention over the prior art and also exists in relation to the above-mentioned methods which are not yet part of the prior art in that you have a large amount of difficult to handle, flammable and expensive aluminum trialkyl can be replaced by a cheap, safe Metallfiuorid.

The amount of aluminum monoalkyl dihalide, which contains a TiCl ₃ , which is produced by reacting TiCl ₄ and organoaluminum compounds, can easily be calculated from equation III, since the rates of the reactions according to equations III and IV are about 200: 1;

ie that in practice the conversion according to equation IV only takes place when AlR ₂ Hal is consumed according to equation III.

It is advantageous to use halogen-containing organoaluminum compounds of the AlR ₂ Hal (R = alkyl

with up to 6 carbon atoms, aryl), such as diethyl aluminum monochloride, or the technically particularly easily accessible alkyl aluminum sesquihalides to be used as reducing agents. The reaction of the TiCl ₄ with the organoaluminum compound is expediently carried out in oxygen-free, desulphurized, well-dried, olefin-free petroleum fractions in the boiling range from 80 to 250.degree. But you can also use aromatics, such as toluene, xylene, diethylbenzene or alicyclics, such as cyclohexane, methylcyclohexane, with the same success. The molar ratio of TiCl ₄ to organoaluminum compound can vary within wide limits, e.g. B. from 1: 0.33 to 1:12. The ratio also depends on the number of organometallic residues of the organoaluminum compound. A ratio of 1: 0.5 to 1: 2 is advantageous.

In the manufacture of those to be used according to the invention The rate of reaction is strongly dependent on the concentration of the catalysts Reactants and the temperature. It is the greater, the higher the concentration and the Temperature are. You can prepare the catalyst z. B. in 0.1 to 3 molar concentration

men. It is advantageous to work in an imolar concentration.

The temperature in the production of the catalyst is of great importance. If you take z. B. the implementation the heavy metal compound with the organoaluminum compound at higher temperatures before, e.g. B. at 40 to 100 ° C, then although the conversion rate large, however, in the polymerization of α-olefins, activated in the claimed Way, such a catalyst shows a slow rate of polymerization and leads to Mixtures of amorphous and crystalline polymers. Therefore, it is also useful here to implement To be carried out analogously to an older proposal at temperatures lower than 40 ° C, advantageous below 20 ° C.

When carrying out the reduction of TiCl ₄ with halogen-containing organoaluminum compound, the procedure can be that one reactant, e.g. B. the titanium tetrachloride, presented and fed to the others, but you can also proceed in such a way that both components are introduced into the reaction vessel at the same time.

The addition of aluminum trialkyl or triaryl and metal fluoride according to the invention takes place after the reduction of the TiCl ₄ to TiCl _{3 is} complete. It is advantageous to subject the unwashed _{TiCl 3} suspension to a thermal treatment of about 40 to 150 ° C., analogous to an older proposal.

As a result of this thermal treatment, _{aluminum monoalkyl dichloride included in the TiCl 3} particle diffuses out and goes into solution. The addition of aluminum trialkyl or triaryl and the metal fluoride can also take place directly into the polymerization vessel.

Those metal fluorides which are able to easily exchange their fluorine for chlorine, bromine or iodine are particularly well suited for the process according to the invention, in particular the alkali fluorides, alkaline earth fluorides, but also heavy metal fluorides such as PbF ₂ . The use of sodium fluoride is particularly advantageous.

The polymerization of the olefins of the CH ₂ = CHR type, where R is hydrogen or a hydrocarbon radical of up to 8 carbon atoms, such as methyl, ethyl, propyl, etc., or the interpolymerization of the olefins with one another can be discontinuous or continuous Normal pressure or at low pressures of, for example, 1 to 30 atmospheres are carried out so that either the _{reaction mixture containing the TiCl 3} precipitate and the mixture of aluminum trialkyl and metal fluoride are initially introduced or the three components are added during the polymerization. The polymerization can be carried out in an inert dispersant and / or in the liquid olefin. The polymerization temperature should generally be below 100.degree.

Suitable aluminum trialkyls or aluminum triaryls are those in which the hydrocarbon radical Contains 1 to 6 carbon atoms. The following compounds are particularly suitable: aluminum trimethyl, -triethyl, -tripropyl, -tributyl, -tripentyl, -trihexyl, -triphenyl.

As olefins to be polymerized and copolymerized according to the invention, for. B. Ethylene, Propylene, butene- (l) into consideration.

example

A. Preparation of the reaction mixture serving as the catalyst component

In a 6-1 four-necked flask, with air and moisture connected, 2950 ecm of an olefin-free diesel oil fraction with a boiling point of 200 to 250 ° C and 529.24 g of aluminum ethyl sesquichloride, made from 41 percent by weight of aluminum diethyl monochloride (= 1.8 mol) and 59 percent by weight of aluminum monoethyl dichloride (= 2.46 mol), submitted, the solution cooled to -3 ° C. and 330 ecm of TiCl ₄ (== 3 mol) were uniformly added dropwise over the course of 4 hours while stirring. An internal temperature of 0 ° C. is maintained by cooling. A red-brown fine precipitate of titanium trichloride separates out. For post-reaction, the batch is stirred for 2 hours at 0 ° C. and left to stand at 0 ° C. overnight. The mixture is heated with stirring under a nitrogen blanket for 6 hours at 100 ° C. The content of TiCl ₃ is determined in a known manner by titration with FeCl. ₃ The aluminum monoethyl dichloride content is calculated to be 10.2 mM per 10 mM TiCl ₃ .

The addition according to the invention of the mixture of aluminum trialkyl and metal fluoride can be carried out directly take place in the catalyst storage vessel; in the following examples, alternating amounts were added Put amounts of aluminum triethyl and sodium fluoride in the polymerization vessel (see table).

B. Propylene Polymerization

In a 3.5-1 polymerization vessel equipped with a thermometer, gas inlet tube and stirrer, an olefin-free diesel oil fraction with a boiling point of 200 to 250 ° C. is placed as a dispersant at 50 ° C. with exclusion of atmospheric oxygen and water and the under nitrogen A described aluminum monoethyl dichloride-containing TiClg suspension, in an amount _{corresponding to 20 mM TiCl 3} , and the amount of aluminum triethyl indicated in the table was added. The mixture is stirred about 15 minutes at 50 ° C under N ₂ and then under N _2, the amount of sodium fluoride shown in the table is added and stirred again for 10 minutes under N ₂ blanketing. Propylene is then passed into the reaction mixture to the extent that it is taken up. The polymerization starts immediately. The temperature is kept at 50 ° C. by cooling. After 5 hours, the polymerization is stopped by adding 80 ecm of butanol, stirred three times with 500 ecm of water each time, the suspension is suctioned off on a suction filter and the residue is washed twice on the suction filter with a warm dispersant. Steam distillation is carried out to completely remove the dispersant from the originally soluble polypropylene. Drying takes place in vacuo at 70 ° C. The insoluble polymer is characterized by its reduced viscosity (0.1% solution in decahydronaphthalene at 130 ° C.).

A sample is used to determine the amorphous or oily content in the polymerization dispersant Worked up as follows: The polymer dispersion is filtered off with suction, the residue is washed out thoroughly and the mother liquor and the combined washing solutions concentrated to dryness in vacuo.

Propylene polymerization

(20 mM TiCL suspension, prepared according to A, 21 dispersants, 50 ° C, 5 hours)

Granted
A1 (C ₂ H ₅ ) ₃ amount in ecm Granted amount
of NaF ing Molar ratio
Al (C ₂ H ₅ ) ₃ : Na F: Insoluble crystalline polypropylene 94 ! >? "<, ***) in mM 0.575 inmM 0.685 Al (CoH ₅ ) Cl ₂ *) g / gTiCl ₃ / hour 97 7.3 4.08 0.863 16.32 0.6 0.2: 0.8: 1 7.3 95 , 8.3 6.12 1.15 14.28 0.514 0.3: 0.7: 1 10 95.3 , 8.5 8.16 1.45 12.24 0.428 0.4: 0.6: 1 12th 96.3 ! 8.8 10.2 1.73 10.2 0.343 0.5: 0.5: 1 14th 96.5 ! 9.2 12.24 2.01 8.16 0.257 0.6: 0.4: 1 17th I 10.58 14.28 6.12 0.7: 0.3: 1 20th

*) 20mM TiCl ₃ suspension contain 20.4 mM Al (C ₂ H ₅ ) Cl ₂ . **) Based on the total polymer.
***) Measured 0.1% in decahydronaphthalene at 130 ° C.

Claims (3)

PATENT CLAIMS: 1. Process for the polymerization and copolymerization of olefins of the general formula CH ₂ = CHR, where R represents hydrogen or a hydrocarbon radical of up to 8 carbon atoms, with catalysts made from reducible compounds of heavy metals from IV. To VI. Subgroup of the Periodic Table, especially TiCl ₄ , and organoaluminum compounds, which may also contain halogen, characterized in that catalysts are used which are obtained by treating the reaction mixture formed by the reaction of the heavy metal compound and organoaluminum compounds with aluminum trialkyls or aluminum triarylene, the Hydrocarbon radical of the aluminum compounds mentioned contains 1 to 6 carbon atoms, and metal fluorides have been obtained or are formed during the polymerization. 2. The method according to claim 1, characterized in that that one uses catalysts in which the ratio of aluminum trialkyl to metal fluoride to aluminum monoalkyl dihalide, that results from the reduction of the heavy metal compound is 0.1: 0.9: 1 to 0.9: 0.1: 1. 3. The method according to claim 1 and 2, characterized in that catalysts are used, which have arisen or are formed by the addition of sodium fluoride as metal fluoride. Considered publications:
British Patent No. 795182. © 109 620/469 6.61